Investigation on the therapeutic effects and the mechanism of mesenchymal stem cells on acute immune liver injury in mice

Abstract

Objective To explore the mechanisms of mesenchymal stem cells (MSC) in the treatment of concanavalin A (ConA)-induced acute immune liver injury in mice. Methods MSC were isolated and cultured from bone of the four limbs of three-week-old C57BL/6 mice. The specific surface markers were identified and osteogenic, adipogenic differentiation ability were tested. A total of 15 six to seven-week-old C57BL/6 mice were divided into control group, MSC treatment group and phosphate buffer saline (PBS) treatment group, five mice in each group. The mice of MSC treatment group was injected through tail firstly with ConA and then MSC, PBS treatment group was injected through tail firstly with ConA and then PBS, control group was injected through tail with PBS twice. The mice were sacrificed in 14 to 16 hours after injection. The level of alanine aminotransferase (ALT), aspartate transaminase (AST) in peripheral blood were detected and the pathological change in liver tissue was scored by Knodell score system. Activation rate of splenic CD4+ T cells and the proportion changes of T hepler cell (Th)1, Th2, Th17 and regulatory T cells (Treg) were detected by flow cytometry and the ratio of Th17/Treg was calculated. The levels of tumor necrosis factor α (TNF-α), interferon (IFN)-γ and interleukin (IL)-4 in peripheral blood were detected by enzyme linked immunosorbent assay (ELISA). Independent-sample t test was used for comparison between groups of measurement data. Results ALT, AST and Knodell score of MSC treatment group was (174.2±46.9) U/L, (185.6±71.6) U/L and 3.4±1.3, respectively, which were better than those of PBS treatment group ((647.0±118.0) U/L, (749.0±104.0) U/L and 5.2±0.8, respectively), and the differences were statically significant (t=8.33, 9.98 and 2.55, all P 0.05). However, in MSC treatment group, the proportion of Th1 and Th2 in CD4+ T cell ((1.83±0.52)% and (2.75±1.06%)), the ratio of Th17/Treg (0.18±0.02) and the levels of TNF-α, IFN-γ and IL-4 in peripheral blood ((760.71±73.19) U/L, (742.49±76.46) U/L and (825.76±101.74) U/L) significantly decreased compared with those of PBS treatment group, and the differences were statistically significant (t=9.45, 4.48, 6.41, 10.14, 5.56 and 10.22, all P 0.05). Conclusions The therapeutic effects of MSC on ConA induced acute immune liver injury were through influence splenic CD4+ T cell subsets by decreasing the proportion of Th1 and Th2 and then declining the levels of secreted cytokines such as TNF, IFN-γ and IL-4 in peripheral blood, increasing the proportion of Treg and decreasing the proportion of Th17 and keeping the balance of Th17/Treg. Key words: Mesenchymal stem cells; Concanavalin A; Liver disease; Therapy; T-lymphocyte subsets